(57) A catalytic hydrocarbon reformer comprising a catalyst concentrically disposed within a reformer tube surrounded by an annular flow space for air entering a fuel-air mixing zone ahead of the catalyst. The catalyst is sustained by minimal insulative mounting material so that most of the side of the catalyst is exposed for radial radiative heat transfer to the reformer tube for cooling by air in the annular flow space. The forward portion of the mounting material preferably is formed of a thermally-conductive material to provide radial conductive cooling of the entry of the catalyst to prevent overheating during catalysis. The incoming air flow is protected from heat exchange with hot reformate exiting the catalyst, allowing for convective cooling of the catalyst side and greater cooling of the catalyst face, thus increasing the working life of the catalyst while providing for rapid startup of the reformer and associated fuel cell system.